This invention relates in general to electronic circuit modules and in particular to an improved structure for an enclosure for such an electronic circuit module.
Electronic circuit modules are well known in the art and are typically composed of an enclosure which protectively houses one or more electrical components and associated electrical conductors. The enclosure is usually formed from a rigid metallic material. Typically, the electrical components and electrical conductors are mounted on one or more flat rigid printed circuit boards. The printed circuit boards are mounted within the protective enclosure to form the electronic circuit module.
As is well known in the art, when electric current flows through an electrical component, heat is generated therein. This heat, if not dissipated, can damage the electrical component. This is particularly true when the electrical component is housed within the protective enclosure of an electronic circuit module, where cooling air cannot flow freely thereabout. Thus, most known electronic circuit modules provide a heat sink to dissipate the heat generated by the electrical components contained within the enclosure. The heat sink is a relatively large mass of thermally conductive material, such as metal, which conducts heat away from the electrical component and the interior of the enclosure to a location where the heat may be dissipated into the air. As a result, the temperature of the electrical component is maintained within a predetermined operating range so as to prevent damage thereto.
To effectively perform this heat transferring function, the electrical component must be maintained in direct physical contact with a surface of the heat sink. To accomplish this, known electronic circuit modules have employed fixed devices, such as threaded fasteners, soldered straps, and the like, to mechanically secure the electrical components to the heat sink. Although these fixed devices have functioned satisfactorily in the past, it has been found that they were somewhat inconvenient to use with differing printed circuit boards. This is because the electrical components of a first printed circuit board were not located in the same positions as the electrical components mounted on a second printed circuit board. Because the locations of the fixed devices on the enclosure were not readily movable, it was difficult to accommodate the differing locations of the electrical components on differing printed circuit boards. As a result, known enclosures for electronic circuit modules have been relatively complicated and expensive to manufacture and assemble for use with differing printed circuit boards. Thus, it would be desirable to provide an improved structure for an enclosure for an electronic circuit module which can easily accommodate the differing locations of the electrical components on differing printed circuit boards.
Additionally, it has been found that these fixed devices tend to become loosened as a result of the repeated heating and cooling cycles experienced when the electrical component is turned on and off. Such loosening can reduce the direct physical contact between the electrical components and the heat sink and, consequently, adversely affect the ability of the heat sink to conduct heat away from the electrical components. Also, it has been found that the repeated heating and cooling can cause flexing of the printed circuit board and, as a result, undesirable stress on the electrical components. Thus, it would also be desirable to provide an improved structure for an enclosure for an electronic circuit module which provides an effective heat sink for the electronic components without generating undesirable mechanical stresses.